Final answer:
The maximum blood-alcohol concentration (B.A.C.) for a learner driver under 25 years of age varies by country and state.
Step-by-step explanation:
The maximum blood-alcohol concentration (B.A.C.) for a learner driver under 25 years of age varies by country and state. In the United States, most states have adopted a zero tolerance policy for drivers under 21, meaning that any detectable amount of alcohol in their system can result in penalties. For drivers over 21, the legal limit is typically 0.08% B.A.C. However, for learner drivers under 25, many states have stricter limits, such as 0.02% B.A.C.